Starr Saphir says, in the 2012 HBO documentary Birders: The Central Park Effect, that there wasn't much money in offering bird walks Central Park, as she had at that time for nearly 30 years, but she's doing something she loves. "I don't look forward to retiring," she explains. "I am enormously lucky in that I absolutely love what I do every day that I do it. It doesn't mean that it's not tedious for moments, or for hours, or the day when you have to come up with 38 birds and the birds are not cooperating, and you end up with 37. It's work. But I could keep this up for, I think, for hundreds of years. Nobody gets a chance to find that out."

Saphir, who logged sightings of 259 bird species just in Central Park (and spoke to NPR's Margot Adler for a 2012 story about birding apps, and, as The New York Times pointed out in a recent story about the film, once took Conan O'Brien around), died on Tuesday. According to her web site, she'd had breast cancer for 11 years. In the film, she spoke of her fatigue during migration season. "At the end of every walk, I can barely get myself home, and I just kind of collapse into bed." And every June, once that season ended and there weren't so many birds to look at, she said, she'd have her annual round of consultations with her oncologist.

If you watch Birders, you'll see not just the strange little world of Central Park's birds and birders, but the reasons people pick up this particular hobby. Birders tend to be patient and detail-oriented, attuned to nature and comfortable in silence. Saphir seems to be even more aware than most of the fact that in some ways, humans are honestly just visiting the birds' delicate environment. "I'd like to see it," her friend Catherine says of a specimen she's trying in vain to spy with her binoculars. "I know," Saphir tells her sympathetically. "I'm not sure it would like to be seen, though."

"Time has a different meaning for birders," she says while discussing her own situation. "You see the changes really from day to day and from week to week. In foliage, in the bird populations, and so on." She continues: "Time has a slightly different meaning for me now that I have terminal breast cancer. I have a great deal more enjoyment. It's heightened my joys in life. And I always loved what I did. But it's heightened even more because I know it's — not only is it not going to last forever, it's not going to last all that much longer."

Birders: The Central Park Effect is a relatively breezy hour long, and it will be airing on HBO this Saturday, February 9, at 6:00 AM Eastern. It's well worth setting your DVR if you have one.

The film Birders: The Central Park Effect is available on DVD, will be on HBO's regular On Demand service beginning February 13, and is now available on HBO GO, the network's streaming service. (At HBO GO, it's under "Documentaries.")